Fix incorrect default for xaxes/yaxes tickColor.
Fix incorrect default for xaxes/yaxes tickColor.

The way in which xaxes/yaxes inherit options from xaxis/yaxis resulted
in a minor bug, where tickColor defaulted to the xaxis/yaxis color
instead of the color for its axis.  Fixed by applying the default before
extending the per-axis options, resolving #984.

There's still some questionable behavior here; this section should be
revisited for 0.9, especially with an eye towards removing some of the
code that only exists for backwards-compatibility.

soenter/flot,resnick1223/flot,saike/flot,matong/flot,k-joseph/flot,TrainingPeaks/flot,flot/flot,cipix2000/flot,resnick1223/flot,gdseller/flot,mlitwiniuk/flot,stanislavdavid/flot,chaveiro/flot,andig/flot,stanislavdavid/flot,pepperdata/flot,andig/flot,chiu/flot,andig/flot,chiu/flot,colinhunt/flot,chaveiro/flot,ni-kismet/engineering-flot,MAMISHO/flot,lolifans/flot,cipix2000/flot,magora-suchkov/flot,fashionsun/flot,mlitwiniuk/flot,stanislavdavid/flot,Sensirion/flot,cipix2000/engineering-flot,saike/flot,klarkc/flot,trask/flot,sedran/flot,k-joseph/flot,resnick1223/flot,chaveiro/flot,octavianCraciun/engineering-flot,k-joseph/flot,kongx73/flot,mcanthony/flot,soenter/flot,petrvacha/flot,chiu/flot,saike/flot,mlitwiniuk/flot